.header{
    position:fixed;
    top:0;
    left:0;
    right:0;
    display:flex;
    align-items: center;
    background-color: #ffffff;
    padding:12px 16px;
}
.header a{
    font-size:14px !important;
    display:block;
    padding:0 16px;
    color:#999999;
}
.header a.on{
    color:#000000;
}